Well, for starters, the number of police killed in the line of duty has been on a long downward trend, while the number of people killed by police has been steady or perhaps rising, depending on what statistics you want to look at.
Police work is statistically safer than being a roofer, logger, commercial fisherman, farmer or many other professions. America's 10 Deadliest Jobs
Look at how cops now handle underage drinking. When I was a teenager, the cops came and poured the beer on the ground, or took it with them. Nobody got written up or arrested. Now, the cops come and arrest everyone in sight. This is one of the earlier interactions many people have with the police, and it is far more antagonistic than it was 20 or 30 years ago. And no, I’m not providing a cite. Ask any parent with kids of a certain age.